Atlantic and Pacific halibut are large, bottom-dwelling flatfish farmed in net pens and tanks. Their specific behavioral needs as benthic species create distinct welfare considerations.
Halibut welfare presents distinct challenges because their benthic lifestyle is fundamentally different from the pelagic species more commonly studied in aquaculture welfare research. Halibut need to rest on substrate — tanks without adequate bottom space force them into abnormal postures. Lighting significantly affects their welfare: incorrect light regimes cause chronic postural abnormalities and stress. Malpigmentation in farmed halibut — where the normally white underside develops dark pigmentation — is both a welfare indicator and a commercial problem, suggesting that conditions causing poor welfare also reduce product quality. Their long production cycle means welfare conditions maintained for years influence cumulative welfare outcomes significantly. Grading and handling procedures cause marked acute stress responses that require careful management.